You have to make the IP of your computer which ist connected with the router static.

first download the auto upgrade utility and the right firmware.
right click on the network icon and choose "show network".
a dialog box apears click properties. then click tcp/ip and choose Properties.
make ip e.g. 192.168.1.21 and subnet 255.255.255.0 and gateway
192.168.1.1

then run the auto upgrade utility. you have to choose the firmware etc...